1. Field of the Invention
The present invention relates to an automatic tracking image pickup system for automatically tracking a target to be tracked, and more particularly, to an automatic tracking image pickup system including a camera platform which turns in accordance with a movement of the target to be tracked.
2. Description of the Related Art
In recent years, there has been proposed an automatic tracking camera system which recognizes an object by using an image recognition technology to perform zooming, panning, and tilting control over a camera provided on a camera platform so as to automatically track the object.
In the system described above, it is conventionally necessary to set in advance at which position in an image on a screen a target to be tracked is displayed before automatic tracking is started. As a setting method, Japanese Patent Application Laid-open No. H08-74296 discloses the following method. Specifically, an operator sets a target position of an object to be tracked in an image on a screen by using an operation apparatus. A camera platform is controlled so as to relatively stop the object at the set target position in the image on the screen during the automatic tracking. The related art disclosed in Japanese Patent Application Laid-open No. 2002-171439 uses a control technique of stopping camera-platform control while the object is moving toward a center of the image on the screen and performing tracking control while the object is moving to an outer side of the image on the screen.
In the related art disclosed in Japanese Patent Application Laid-Open No. H08-74296 described above, however, when the object to be tracked moves from the outside of the image on the screen to appear on the screen at the start of the automatic tracking, a large and sudden tracking operation is required to be performed because the position of the object is away from the set target position at that time. Moreover, when the object to be tracked is a moving body which moves in a given direction, if control for capturing the object to be tracked at the target position is performed immediately after the object to be tracked appears in the image on the screen, the tracking operation is performed for a direction opposite to the direction of movement, that is, becomes an unnecessary operation. In the related art disclosed in Japanese Patent Application Laid-Open No. 2002-171439, the control is not started until the object reaches the preset target position in the center of the image on the screen. Therefore, a sudden and unnecessary change in a video image does not occur. However, a relative positional relationship between the object and the target position is changed by the effects of a disturbance in image recognition for recognizing the object as the target to be tracked and the zoom control. Therefore, there is a disadvantage in that the tracking operation becomes unstable.